Former army general Prabowo Subianto, who ran against Joko Widodo for Indonesia's top job last year, says the death penalty is a valid punishment for "drug kingpins" given what he calls his country's drug emergency. Indonesia's national interest should always come first, he says.

But he says he also understands why Australia is doing so much to try and get the men off death row.

"If we keep looking for something negative we will see it as pressure, but if we look at it as a government's effort to protect its citizens I believe it is the country performing its duty," he told the Indonesian news website tribunnews.com.

"We too try to defend our citizens, we also have many citizens on death row."

Fairfax Media has learned that Australian contacts approached Mr Prabowo in an attempt to help save the lives of the two men, who are still awaiting execution on Nusakambangan prison island.

The exact timing and nature of the contact is not clear but Fairfax Media understands the approach did not come directly from the Australian government.

Well-placed sources have described the approach as informal.

Meanwhile, Mr Joko still has not returned a request for a conversation that Prime Minister Tony Abbott lodged more than a week ago.

Mr Abbott on Saturday told Sky News there was still hope for the duo but would not speculate on how strong it is.

"I'm a parent and inevitably you think to yourself, what if those were [people] very close to you? What would you want the Australian government to do for those people? Obviously you'd want the Australian government to make the strongest possible representations, you would want us to be relentless."

Attempted contact with Mr Prabowo is an interesting development, given Mr Prabowo's background as a former special forces commander with a chequered human rights record. The son-in-law of former dictator Suharto, he has been linked to abuses in East Timor and has admitted to kidnapping and torturing protesters in Jakarta in 1998.

To this day, he is banned from travelling to the United States. Australia only lifted a travel ban on him in recent years.

The approach is also an illustration of just how broad Australian attempts to save the men have become, given Mr Prabowo is also Mr Joko's chief political rival.

Mr Joko beat Mr Prabowo in last year's election, and subsequently rejected clemency appeals for the Australians who were busted for heroin smuggling in 2005.

But since the election, Mr Prabowo's popularity has boomed while Mr Joko's has waned. Mr Prabowo wields significant power within the Indonesian parliament.

Fairfax Media sought to contact Mr Prabowo directly but he did not respond.

The developments come a day after Fairfax Media revealed prominent members of Mr Joko's own government have been urging him to reconsider the executions of the Bali nine duo.

Ross Taylor, President of the Perth-based Indonesia Institute, says his trusted sources have also told him about the Prabowo approach.

Mr Taylor called it a "bizarre" development, given most Western governments were quietly relieved Mr Prabowo did not win the election because of the difficulty his human rights record could have posed.

But he says he understands why it was thought Mr Prabowo might be able to help, given his surging influence. He describes Mr Prabowo as a "lion" lying in wait as Mr Joko's government flounders.

Mr Taylor also warns the that the rift between the two countries over the duo's fate is widening and could develop into the most significant schism in relations since the East Timor independence crisis in 1999.

"There's a lot at stake, and it's much more than just our precious Bali holidays," he said.

Meanwhile the Indonesian president's chief of staff has said that it is not possible to commute the Bali nine duo's death sentences.

In an opinion piece in the Straits Times, Luhut Pandjaitan said the prisoner swap proposed by Foreign minister Julie Bishop would be "more appropriate for prisoners of war or spies".

He also said that Australia's threats over damage to the countries bilateral relations should the executions proceed would not work.

"Instead, threats force the affected side to stiffen its position," he wrote.

Mr Luhut also said Indonesians were infuriated by reports that Australian spies targeted Telkomsel, Indonesia's largest mobile network.

"If true, the reports would add grist to the mill of Indonesian perceptions that Australia does not trust Indonesia."